The patent PCT/WO 00/69565 filed in the name of G. Medoro describes an apparatus and method for manipulation of particles via the use of closed dielectrophoretic-potential cages. The force used for maintaining the particles in suspension or for moving them within the microchamber dissipates, by the Joule effect, a power that is proportional to the square of the amplitude of the voltages applied and increases linearly as the electric conductivity of the suspension liquid increases, causing an uncontrolled increase in temperature within the microchamber. The individual control on the operations of manipulation may occur via programming of memory elements and circuits associated to each element of an array of electrodes integrated in one and the same substrate. Said circuits contribute to the increase in temperature by dissipating power in the substrate that is in direct contact with the suspension liquid. There follows an important limitation due to the death of the particles of biological nature present in the specimen for solutions with high electric conductivity limiting the application of said methods and apparatuses to the use of beads or non-living cells.
An example of apparatus that implements said method is represented in FIG. 1, shown in which is the electric diagram of the circuits dedicated to each element of an array of microsites (MS) and the signals for enabling driving thereof. The manipulation of particles is obtained by means of an actuation circuit (ACT) for appropriately driving an electrode (EL), to each electrode of the array there being moreover associated a circuit (SNS) for detection of particles by means of a photodiode (FD).
The limitations of the known art are overcome by the present invention, which enables manipulation of biological particles by means of the described technique of the known art preserving the vitality and biological functions irrespective of the forces used and/or of the conductivity of the suspension liquid. In addition to the possibility of manipulation of living cells, the present invention teaches how to reduce the power consumption and how to maximize the levels of performance of said devices given the same power consumption.